We stayed in room 6315 while in Sugar Loaf. This was a marina view room, on the 3rd floor. It didn't really have a castle view, but we did get to see the fireworks while sitting out on our balcony. I'm not sure if you can request specific room numbers, but I'd go with something on the 3rd floor, marina view, on the end closer to the main building (rooms #6?01-6?15). Conch Key tends to stick out a little bit more and can block the view entirely if your room number goes any higher than 15.